1. Field of the Invention
The present invention relates to a drive unit for a shaft of a device forming a leno selvedge and synchronized with the frames of a mechanical loom.
2. Description of the Prior Art
The document DE 195 48 955 C1 discloses a device for forming a leno selvedge that is provided with an electromotor whose rotors are having two arms arranged like propeller blades. These arms are provided at their end with an eye through each of which a doup end is guided. The rotation of the rotor and thus the rotation of the arms are creating, together with the weft thread, the leno selvedge. In order to avoid a permanent connection of the doup ends in the area of the spools, the sense of rotation of the motor is reversible.
Devices intended to form a leno selvedge and driven by a shaft are known for example out of DE-PS 195 20 500.6. Up to now, such a device is mechanically coupled to the drive unit of a mechanical loom, a further shaft being usually flanged to the driven shaft of a mechanical loom, that means to a shaft that is coupled to the actuation of the mechanical loom and that drives the accessory units. This further shaft may for example be designed as a flexible shaft that drives the shaft of the device for forming a leno selvedge. It is necessary to have the device for forming a leno selvedge directly driven by a corresponding driven shaft of the mechanical loom because the leno selvedge device has to run in unison with the heald frames of the mechanical loom. That means that the position of the different thread guide elements of the leno selvedge device is depending on the position of the heald frames and subsequently on the angle of aperture of the shed.
Modern mechanical looms often proved to no more have a need for a driven shaft for accessory units, as for example a leno selvedge device, that could be used as actuation for such a device. And even when a mechanical loom is provided with such a driven shaft, the shaft often has such a disadvantageous position that the mechanical coupling between the driven shaft and the shaft of the leno selvedge device require complicated measures.